How to Grow Organic Food like Medieval Farmers

By Lucie Laumonier

If nothing else works, you could bring the vermin to justice.

As soon as humans started farming in the Neolithic age, they had to protect their crops from hungry insects. Until the invention of modern herbicides, pesticides and insecticides, farmers used various products to repel pests and to enhance the crops’ production. Medieval agriculturalists used natural but sometimes toxic products to protect their crops. They practiced what we would call, today, organic agriculture.

Agronomic treatises, concerned with the techniques involved in agriculture, are the main source about medieval crop protection. Among the best known are the anonymous Geoponika, written in Byzantium in the mid-10th century; and Arabic treatises authored around the Mediterranean, such as Ibn al-‘Awwam’s encyclopedia, written c. 1200 in southern Spain. All medieval authors leaned on their Roman and Greek predecessors but added new ideas and techniques they had read about, witnessed or tested.


Medieval farmers, like modern farmers, encountered various issues with their crops: poor yields, bad weather, plant diseases, thefts and pests. But one of the most pressing issues was the damages animals and insects caused to the crops. To repel pests, they employed various techniques, including the use of pesticides. as well as some more interesting methods.

Pesticides and Insecticides

Medieval farmers and agronomists had developed a large number of recipes to pulverize, fumigate or pour on crops to cure their diseases and to repel pests. Their repellents were often plant-based products, but mixtures with sulfur, urine and vinegar were common. A well-liked non-botanical pesticide was one-year-old pigeon manure, known to drive away vermin, such as locust and caterpillars. Pitch and ashes, substances that are still found in organic agriculture, were used to prevent pest infestation. Non-vegetal products were, usually, mineral components. Sulfur was the go-to pesticide, which also acted as a fertilizer.

Sulfur is still widely used in organic agriculture where it acts as a plant nutrient, a fungicide and a pesticide. In nature, sulfur crystals are found in minerals extracted by mining. Sulfur also abounds in volcanic regions where it is more easily harvested and existed under a purer form. Sulfur is the first insecticide ever mentioned in European classical texts. Medieval farmers spread it in a thin powder at the base of vineyards to drive away insects. They burned it and fumigated it around vegetable beds to repel ants, caterpillars, and other pests. Sulfur could also help a farmer to get rid of moles, explained the author of the Geoponika if one mixes it with cedar resin and fumigates the mixture in the mole’ burrow.

Miniature of a man at work extracting sulfur. British Library MS Egerton 747 f. 88v

Medieval farmers also used some highly toxic products to protect their crops. The author of the Geoponika recommended pulverizing lead on trees and vines to repel caterpillars. Arsenic was probably the most dangerous product of all. Burnt, it could chase away reptiles and scorpions – pests that posed more issues to humans than to plants. Arsenic was also useful to kill birds. Ibn al-‘Awwam suggested to “boil wheat with red arsenic and then throw it to the birds; those who eat it will die without being able to fly away.” Toxic plants like ivy were sometimes affixed at the bottom of grapevine stems to drive away ants and beetles.

Farmers preferred to use “botanical” pesticides – that derived from plants. Garlic, for instance, offered versatility. Mashed, it repelled caterpillars in vines; fumigated, it would drive wasps away, wrote fourteenth-century Andalusian agronomist Ibn Luyun: “to frighten the wasps, garlic grated in olive oil should be burned. This is a proven method.” The Geoponika recommended hanging garlic in fruit trees to repel birds. Medieval agronomic treatises listed dozens and dozens of plants that could be used to control various pests after their processing. Farmers used crushed plant parts, watery extracts, plant powder, concentrates obtained by heating plants, the list continues.

Putting insects on trials

For bountiful harvests, to repel pests and to ensure good weather, medieval farmers could turn to God. Prayers, blessings and processions destined to protect the crops were a common feature of the medieval era. The Rogation processions served this particular purpose. Held during Eastertide, the Rogations corresponded to three days of religious celebrations during which parishioners, led by the local clergy, circulated in the fields and asked God to protect the harvests. Processions were also organized in case of climatic catastrophes, plagues of insects and poor harvests. If nothing worked against pests, farmers could turn to an ecclesiastical court of justice.


The clergy would try to force the insects—often the cause of the complaint—out of the estates. Clerical interventions ranged from prayers to written orders and went insofar as to properly trial the pests and, sometimes, excommunicate them. In 1478, white grubs or caterpillars were causing problems to farmers of the parish of Berne, Switzerland. The priest carried their grievances to the bishop of Lausanne, who drafted a written order to the worms to make them leave the premises within six days. At Berne, the worms were informed of the eviction notice after mass. The priest and parishioners helped with their prayers. The city council of Berne even organized a public prayer to ask God to repel the worms. Unfortunately, it did not work and farmers asked, again, the bishop’s help. In the Spring of 1479, the worms were properly put on trial in the court of justice and excommunicated by the bishop.

Trials of animals were not uncommon in the Middle Ages. Oftentimes, mammals were accused of having killed humans. The judicial procedures followed the usual human trials. Lawyers pleaded their case to the court before their inevitable condemnation. In the case of insects, exile to uncultivated lands coupled with anathema or excommunication was the usual punishment. But the afflicted farmers had a role to play. They should repent and pray: plagues of insects were God’s punishment for human sins. The custom of prosecuting animals emerges pretty early in the medieval era. But excommunications of insects only appeared at the end of the fifteenth century. They became commonplace in the early modern era.

The lawfulness of such excommunications was disputable. Theologians usually agree that the measure was useless because animals are creatures of God, neither good nor evil. They are not reasonable beings – that is, they cannot reason and understand. Finally, the point of excommunication was to deprive a Christian of communion at church, and animals were not parishioners. The excommunication of animals and insects was construed alternatively as a sort of malediction or exorcism, or as an adjuration. Thomas of Aquinas, in the thirteenth century, wrote that the adjuration of animals functioned as a plea to God, a sort of prayer asking him to free the humans from their wrongdoings.


From hunting to scaring birds away

Medieval authors discussed the damages caused by domestic animals, such as cattle, goats and pigs, as well as the destructions of wildlife: birds, boars, rabbits, foxes and the like. Damages caused by wild animals could be extensive and were difficult to prevent. In 1225, two farms located in Germany were sold “because they lay waste and were spoiled by the wild beasts, so that they brought no profit”. In the French royal forests, in 1483, there was “great waste of wheat by wild beasts, which men dare not touch.” Boars were usually at fault. With their tusks and snout, they dig into the ground, uproot crops and lay complete devastation. But medieval peasants did not have the right to hunt boars. Hunting rights were complex in the medieval era, but the hunting of boars was usually a lord’s privilege. Some peasants could trap the animals but were not allowed to kill them.

Detail of a miniature of a nobleman spearing a snared boar. British Library ms Egerton 1146 f. 12v

The situation was even worse when the damages were caused by animals the lord owned. In 1340, the parishioners of the manor of West Wittering, England, claimed that “the wheats in the said parish have been devoured year after year by the rabbits of the bishop of Chichester, and thereby lessened in value.” Same story at Ovingdean, where 100 acres of arable land had been “annihilated by the destruction of the rabbits of the lord Earl Warenne.” Needless to say, the peasants could not kill their lords’ rabbits! These animals were probably introduced into England in the high medieval era, although evidence suggests that some specimens had been kept as pets before then. Their introduction en masse caused problems to farmers who complained for decades against the devastations of the wild rabbits.

Birds were another issue. Flocks are often represented on illuminations following the peasants’ sowing. Worse, they could devastate a mature cereal field right before its harvest. They also prey on fruits and were often seen in the vicinity of orchards.  German author Konrad von Megenberg, writing c. 1350, complained that “in autumn, [the starlings] cause great damage in the vineyard”. Late medieval illuminations show that threads and nets were affixed between poles to protect freshly sown fields from birds. In vegetable beds, the seeded plots were sometimes covered with thorny branches. Sources indicate that boys were employed to chase the birds from sown fields of cereals by making loud noises or by throwing stones at them. Scarecrows are first mentioned by Sevillan agronomist Abū ’l-Khayr al-Ishbīlī in his treatise written in the late eleventh or early twelfth century.

A Plague of Insects

Insects caused the most damages. Dreaded were the migratory locusts – like in the Bible, they appear suddenly, devour everything and leave humans in disarray. In 873, and during two months, western Germany was the prey of large swarms of migratory locusts that devoured everything green, a Frisian chronicle reported, including the barks and branches of trees. Another “plague” of locusts fell on Italy in 1337. The Byzantine author of the Geoponika recommended mass collection and killing of the locusts: “When you come before the rise of day, you will find them in the holes plunged in sleep; how to kill them is your business.”


When possible, crops and fruits should be physically protected from insects. Farmers could apply greasy or sticky substances on the trunk of trees and vines to prevent critters from crawling up. Hornets, feared for their aggressiveness, posed another threat. Some authors recommended wrapping grapes in combed wool or linen rags to protect them from hornets. Another option was to plant bait plants that would attract insects and drive them away from the “real” crops. Chickpeas, for instance, attracted snails, which were then hand-picked and killed by the farmers. The larger critters, such as grasshoppers, crickets, snails, caterpillars and slugs were usually dealt with by hand. In the vineyards of France, women and children were responsible for handpicking snails and slugs.

Locusts on a tree – British Library MS Additional 27210 f. 13

Medieval farmers practiced a sort of organic agriculture, in a manner we now see as being traditional. But, from the point of view of medieval agronomists, their advice placed farmers at the cutting edge of agronomic innovation. Farming has been revolutionized in the twentieth century by the broad recourse to heavy pesticides responsible for water and soil pollution. Many modern pesticides are also correlated to the extinction of insects, such as the bees, and to human diseases, like cancer. Modern farmers who embrace organic agriculture are going back to the roots of their profession.

Lucie Laumonier is an Affiliate assistant professor at Concordia University. Click here to view her page or follow her on Instagram at The French Medievalist.

Further Reading:

Richard Almond, Medieval Hunting, Sutton, 2003

Thomas F. Glick, ‎Steven Livesey, ‎Faith Wallis (eds), Medieval Science, Technology, and Medicine: An Encyclopedia, Routledge, 2005

G. G. Coulton, The Medieval Village, reprint 1989

Jan C. Zadoks, Crop Protection in Medieval Agriculture: Studies in Pre-Modern Organic Agriculture, Sidestone Press, 2013

Click here to read more from Lucie

Top Image: Bibliothèque nationale de France MS Français 126 fol.7r


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